JP2002331406A - Abrasion resistant coating film-covered tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coating film-covered tool remarkably enhancing lubricity of a coating film, restraining a rise in a cutting temperature, and superior in oxidation resistance and adhesion for coping with drying and speedup of cutting work of highly hard steel, and provide a composite hard coating film-covered tool further superior in adhesion by a combination with a conventional coating film. SOLUTION: This abrasion resistant coating film-covered tool is formed by covering a base body surface with a hard coating film of at least one layer (TiAl) system. The lubricity is improved by adding S. The coating film is constituted by being covered with the hard coating film further improved in the lubricity by substituting a part of S with B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard film-coated tool used for high-speed cutting of a tool made of cemented carbide and high-hardness steel.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Sho 62-56565 discloses the direct cutting of tempered steel for the purpose of improving the efficiency of metal working.
TiAlN represented by JP-A-2-194159
Coatings have been developed and applied to cutting tools. TiAlN
Since the coating has better oxidation resistance than TiN and TiCN, the performance of the cutting tool is remarkably improved in cutting of tempered steel whose cutting edge reaches a high temperature.

However, in recent years, in order to meet the demand for higher efficiency and higher precision of processing, dry cutting has been regarded as important in view of environmental problems and reduction of processing cost in addition to increasing the cutting speed. I have. In such a cutting environment, the welding phenomena between the wear-resistant film coated on the cutting tool surface and the material to be cut (hereinafter referred to as the work material) has a great effect on the cutting performance, and the cutting temperature decreases. As the temperature becomes higher, oxidation resistance is not sufficient even with a TiAlN-based film. In other words, the conventional TiN, TiCN and TiAlN coatings have sufficient cutting performance under such a severe cutting environment due to an increase in frictional resistance and oxidation progress caused by a welding phenomenon with a work material and the like. I ca n’t get it
At present, the progress of wear due to oxidation cannot be sufficiently suppressed.

In order to solve such a problem, molybdenum disulfide disclosed in JP-A-11-502775 and JP-A-7-164211 are disclosed from the viewpoint of improving the welding resistance.
A cutting tool has been developed in which a lubricating film consisting of tungsten carbide and diamond-like carbon is laminated on the outermost surface of the hard film, but the adhesion of the hard film to the film is poor and the film itself is very brittle. It is poor in oxidation resistance, and cannot be adequately treated in the above-mentioned cutting environment due to peeling or destruction during cutting, oxidative wear, and the like.

From the viewpoint of improving oxidation resistance, Japanese Patent Application Laid-Open
Although there is a case where a third component is added to TiAlN as typified by JP-A-237010 and JP-A-10-130620, the improvement in oxidation resistance that is sufficiently satisfied only by the addition of the third component is not achieved. The reality is that it has not been realized. Japanese Patent Application Laid-Open No. 8-118106 discloses Ti
Although the case of SiN has been proposed, mere TiSiN has not been able to improve the oxidation resistance and has not been able to lower the cutting temperature itself.

[0006]

SUMMARY OF THE INVENTION In view of these circumstances, the present invention can cope with dry and high-speed cutting, that is, it has excellent oxidation resistance, has low adhesion to a work material, and has low lubricity. We propose a hard layer to have, reduce the cutting temperature,
An object of the present invention is to provide a wear-resistant film-coated tool capable of simultaneously realizing oxidation resistance and welding resistance and capable of dry cutting high-hardness steel at high speed. In summary, in dry high-speed cutting of hard materials rather than oxidation resistance, it is extremely important to reduce the cutting resistance itself and suppress the rise in cutting temperature while maintaining the oxidation resistance of the film. It is an issue to reduce the cutting temperature.

[0007]

The inventor of the present invention has conducted detailed studies on the wear resistance of a hard coating, its effect on various work materials and reduction of frictional resistance, and the layer structure of the coating. It was found that metal components diffused inside the film due to high temperature, and the fact that the diffusion rate varied depending on the crystal orientation of the whole film was verified. In other words, it was demonstrated that the cutting temperature can be significantly reduced by selecting a metal component in which the metal component easily diffuses to the coating surface and a metal component that diffuses to the coating surface to impart lubricity. The hard coating is desirably coated by a physical vapor deposition method.

[0008]

Function First, the function of the hard layer will be described in detail. The present inventors have intensively examined various metal components, and as a result, the metal component in the coating is internally diffused from the cutting heat to the coating surface, and the diffusion component itself imparts lubricity,
Oxidation on the film surface, the oxide itself provides lubrication, and the formed oxide has an extremely low melting point and may provide lubrication by liquefying the low melting oxide. confirmed.

[0009] S and B are examples of the components that function as lubricating components by themselves. Si that forms an oxide, and the oxide itself functions as a component that imparts lubrication is Si. V, Li, and the like are examples of a component that imparts lubricity when the formed oxide has an extremely low melting point and the low-melting oxide liquefies. According to the study results of the present inventors, in the case of adding S, the effect of S diffused to the surface and the addition of S (TiAl
S) It was confirmed that the synergistic effect of the lubricity of N itself has the highest lubricity. Furthermore, it was confirmed that the cutting temperature can be further reduced when the diffusion component itself is used in combination with B, which imparts lubricity.

It is also an important finding that the crystal orientation of the film is a very important factor in determining the diffusion rate of the metal component. If the (111) plane, which is a close-packed surface, has the highest diffraction intensity, that is, if the (111) plane, which is a close-packed surface, has a high probability of being parallel to the tool surface, the diffusion of the metal component to the surface, That is, diffusion in the direction perpendicular to the tool surface becomes difficult. This suggests that the densely packed surface acts as a barrier to diffusion. Therefore, the crystal orientation is (200) more than the (111) plane.
If the plane or the (220) plane has the highest diffraction intensity, the metal component is more easily diffused. (220)
In order to impart the highest diffraction intensity to the surface, the coating conditions are restricted, and as a result, the adhesion of the film may be deteriorated.
The most preferable result is to give the (00) plane the highest diffraction intensity.

The composition of the S metal element in the hard layer constituting the hard coating of the present invention is more preferably 0.5 atomic% or more and 20 atomic% or less. When the content is less than 0.5 atomic%, lubricity is imparted but the effect is small. When the content is more than 20 atomic%, the hardness of the film may be reduced depending on the coating conditions. Also, as the S content increases, the adhesion of the film tends to deteriorate, and the S content on the base material side is low,
It is most preferable to employ a so-called gradient composition of S in which the S content for imparting lubricity is increased toward the surface.

Further, the substitution amount of B is 0.5% with respect to the whole film.
If the content is less than 10 atomic%, the effect is not recognized. If the content is more than 10 atomic%, the residual compressive stress is increased, and the adhesion of the film is deteriorated.
It is restricted to not less than 10 atomic%.

The hard layer has excellent adhesion, low friction and high oxidation resistance under static and dynamic conditions,
In dry high-speed cutting of high-hardness steel in which C exceeds 60, a single coating may not have sufficient adhesion and peeling may occur. Therefore, it is sometimes preferable to form a laminate using a (TiAl) N hard layer or the like having excellent adhesion resistance and abrasion resistance and an underlayer as such an underlayer, in such a high hardness steel cutting.

It goes without saying that the (TiAl) N layer used here may have the same effect even if the third metal component is added in some cases.

The method for coating the hard film-coated tool of the present invention is not particularly limited, but in consideration of the thermal effect on the coated base material, the fatigue strength of the tool, the adhesion of the film, etc. Arc discharge ion plating that can be coated at a relatively low temperature and compressive stress remains in the coated film,
Alternatively, a physical vapor deposition method of applying a bias voltage to the coated substrate side such as sputtering is preferable.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Using an arc ion plating apparatus having two arc evaporation sources and one magnetron sputtering evaporation source,
A target made of various alloys, which is an evaporation source of metal components, and a target which can obtain a target film from N ₂ gas, which is a reaction gas, are selected.
Under a condition of 8 Pa, a potential of -100 V is applied to a coated cemented carbide 2-flute end mill having an outer diameter of 10 mm and a cemented carbide insert, and the total coating thickness is 3 μm. Filmed. The amount of B added was adjusted by adjusting the amount contained in the TiAl metal arc target.
S was added by magnetron sputtering using a MoS ₂ target. In this case, S was added to the (TiAl) N film in combination with the arc ion plating method. The amount of S added was adjusted by adjusting the discharge current value in arc and magnetron sputtering. In multi-layering with another layer, the thickness ratio of the S-containing layer to the other layer was 1: 1. When S is added, M
Although o is also added, Mo does not particularly affect the performance. Similarly, when a TiS target is used, Ti is inevitably added. The composition ratios of the examples show the ratios when Ti + Al + S excluding Mo content is 100%.
The composition change indicated by → indicates the composition inside the film and the composition at the outermost surface. The amount of S added is determined by adjusting the discharge current value.
The content was graded.

[0017]

[Table 1]

A cutting test was performed using the obtained hard film-coated end mill and hard film-coated insert. The tool life was defined as the cutting length when the tool could not be cut due to chipping or wear of the cutting edge. Table 1 also shows the obtained results.

The cutting conditions of the two-blade carbide end mill are side cutting down cut, work material S50C (hardness HB22
0), incision Ad10mm × Rd1mm, cutting speed 1
50 m / min, feed 0.06 mm / tooth, and use of air blow.

The insert cutting conditions are as follows: Tool shape SEE4
2TN, 100mm width x 250mm length chamfering,
Work material SKD61 (hardness HRC45), depth of cut 2.0
mm, cutting speed 120m / min, feed 0.15mm /
rev, dry cutting. Table 1 also shows the test results.

The cutting temperature was measured by lathing. The measurement was performed by measuring the thermoelectromotive force generated between the workpiece and the coated insert during cutting using the thermoelectromotive force method. The work material used was S53C and the cutting condition was a cutting speed of 30.
0m / min feed 0.25mm / rev cut 2mm
It is dry type. The measurement time was 10 seconds and the final cutting temperature was used. Table 2 shows the results. Further, the friction coefficient between the coated tool and the ball was measured at 650 ° C. using a ball-on-disk using an S53C ball. The results are also shown in Table 2.

[0022]

[Table 2]

Comparative Examples 19 and 20 are comparative examples in which the amount of B is too large. Although the static evaluation values are satisfied, the adhesion is not sufficient and the tool life is short. Comparative Examples 21 and 22 are the same (TiAlS) N-based film, but have the highest diffraction intensity on the (111) plane depending on the coating conditions (1).
11) It is apparent that the surface diffusion of S is not sufficient and the cutting temperature does not decrease due to the orientation. Comparative Example 15,
Examples 16, 17, and 18 are examples in which the third component is added to the TiAlN-based coating, and although the oxidation resistance is improved, the improvement effect is less than that of the present invention from the viewpoint of lowering the cutting temperature.

On the other hand, the examples of the present invention are excellent in static evaluation characteristics, low in cutting temperature, excellent in adhesion, and at the same time, cause abnormal wear, oxidized wear of the film and peeling of the film due to the welding phenomenon. None, and the overall tool life is significantly improved. Therefore, the present invention is sufficient for dry high-speed cutting of high hardness steel.

[0025]

As described above, the hard-coated tool of the present invention is superior to the conventional coated tool, particularly effective in reducing the cutting temperature, and has both high adhesion and high oxidation resistance. Therefore, a significantly longer tool life can be obtained in dry high-speed cutting, which is extremely effective for improving productivity in cutting.

Claims (4)

[Claims] 1. A substrate surface coated with at least one layer of a nitride, carbonitride, nitride oxide, or boride having Ti and Al as main components having the strongest diffraction intensity in the (200) plane in X-ray diffraction. In a coated tool, the at least one hard coating has a T
A tool with a wear-resistant coating, wherein i is partially replaced by S. 2. The tool as claimed in claim 1, wherein said S content is at least 0.5 atomic% and at most 20 atomic%. 3. A tool with a wear-resistant coating according to claim 1, wherein the content of S is higher in the surface of the coating in the coating. 4. The tool according to claim 1, wherein a part of said S is substituted with B in a range of 0.5 atomic% to 10 atomic% with respect to the whole coating. Wear-resistant film-coated tools.